Floating fork for bicycles



Patented Jan. 5, 1943 FLoATING FORKFOR BICYCLES Harry W. Kranz,Lakewood, Ohio,y assigner to The Cleveland Welding Company, Cleveland,Ohio, a corporation of Ohio Application May 3, 1940, Serial No. 333,17()

1 Claim.

This invention relates, as indicated, to a kneeaction or floating forkfor bicycles whereby the eiects of road bumps and the like may be muchlessened, ensuring both greater comfort for the rider and a. longer lifefor the bicycle.

'The chief source of discomfort to riders or bicycles has been thejarring and jolting Occasioned by striking obstructions such as curbingand other irregularities in the road, the resulting shock also tendingto bend the front fork. It is, therefore, a primary object of thisinvention to provide a device of the character described which will beeiective to take upI shock when the front Wheel of a bicycle encountersan obstruction and absorb the jolts and jars which otherwise reach therider.

Another object of this invention is to provide such device which shallbe inexpensive to manufacture and simply assembled.

Still another object is to provide a resilient mounting for the frontfork members of the bicycle which will not require servicing orreadjustment.

Other objects of the invention will appear as the description proceeds.

To the accomplishment of the foregoing and related ends, said invention,then, consists of the means hereinafter fully described and particularlypointed out in the claim.

The annexed drawing and the following description set forth in detailcertain mechanism embodying the invention, such disclosed meansconstituting, however, but one of various mechanical forms in which theprinciple of the invention may be used.

In said annexed drawing:

Fig. 1 is an elevational view of one embodiment of my new fork andresilient mounting means in cross section taken along the line I-I onFig. 2;

Fig. 2 is a front elevational view lof such fork with a portion brokenaway to show the arrangement of parts of the resilient mounting means;

Fig. 3 is a fragmentary front elevational View (enlarged) of the forkbrace and upper ends of the fork members;

Fig. 4 is a side View taken along the line 4-4 on Fig. 3;

Fig. 5 is a side view similar to Fig. 4, but in- Fig. 7 is a sectionalview of such means taken along the line 'I-'I on Fig. 6.

Referring now more particularly to said drawing, and especially Figs. 1to 5, one structure embodying my invention may comprise a tubularsteering post I at the lower end of which is rigidly secured a forkbrace 2 by means of stud 3 on said brace which is inserted in said post,the joint then being brazed or welded. Fork brace 2 carries twodependent hook-shaped arms 4 and 5 in which is journalled a tubularsleeve 6 having a stop 'I positioned to engage the forward portion ofbrace 2 when said sleeve is rotated in a counterclockwise direction asviewed in Fig. 1 and to pass between arms 4 and 5 when said sleeve isrotated in a clockwise direction. Passing through said sleeve is aninner pivotal cross member 8 bearing terminal studs 9 and I Il to whichfork members II and I2 are adapted to be rigidly connected as by pins I3and I4. Between said cross member and said sleeve and bonded thereto isdisposed a body of rubber I5 adapted to yieldably resist relativerotation of said cross member and said sleeve. It is thus apparent thatif sleeve 6 be held against rotation and fork members II and I2 be movedcausing cross member 8 to rotate, such rotation will cause internaldistortion 'of the rubber which will torsionally resist the movement. Asshown in Fig. 1, stop I is so disposed as to engage the forward portionof fork brace 2 and prevent counterclockwise rotation of sleeve 6 beyondthe position illustrated in said iigure, and such fork brace alsocarries wing portions I 6 and I'I overlying the upper ends of forkmembers II and I2 respectively. As best shown in Fig. 5, the upper endsof the fork members are rounded forwardly to perm-it of counterclockwisemovement, as shown in such iigure, but the rear portions, such as I8,act as stops engaging the under surface of said wing portions inpreventing clockwise rotation, i. e. preventing rearward rotation of thefork members beyond the position illustrated in Figs. 1 and 5.

The fork of my invention is assembled as follows: Sleeve 6 with rubberI5 and cross member 8 therein is inserted in brace 2, the distancebetween the ends of arms 4 and 5 and the forward portion of the bracemember being suflicient to permit the passage of stop l. Cross member 8has been so positioned inv relation to sleeve 6 that the holes in studs9 and I0 for pins I 3 and I4 are disposed at right angles to the face ofstop 1, i. e. parallel to the axis of the upper portions of fork membersI I and I2 when the latter are positioned as in Fig. 1` and stop 'Iabuts against brace 2.

One of said studs is then seized and cross member 8 rotated 90 in acounterclockwise direction, as viewed in Fig. 1, so that the holes forpins I3 and Id are positioned as illustrated in Fig. 2. Fork members I Iand I2 are then attached. 1t will now be seen that stop 'I will be heldagainst brace 2 by the torsional stress in the rubber caused by theabove described rotation of member 8. It is thus apparent that should arider mount the bicycle, fork members II and I2 will tend to move towardthe right as viewed in Fig. 1 and since sleeve 6 is prevented fromrotation by stop 1 such movement of the fork members and resultantrotation of cross member 8 must entail further distortion of the rubberbody I5, the rotation of the fork arms in this direction being onlylimited by the torsional stresses built up in such rubber. When a bumpor other obstruction is encountered, the fork arms are thus enabled tomove in a clockwise direction as viewed in Fig. 1, although only to theextent permitted by the stop ends such as I8 engaging the aforesaid wingportions of fork brace 2.

As a result of this construction a long lever arm is available betweenthe axle of the front wheel and the fork mounting providing forsensitive response of the resilient cushioning means. Furthermore, suchmounting aiords no occasion for rattles or vibration, but on thecontrary tends to deaden the latter. The rubber body I5 may be bonded tomember 8 and sleeve 6 as by vulcanization or may be so dimensioned as tobe fitted under great compression on such cross member within suchsleeve.

Another embodiment of my invention is illustrated in Figs. 6 and 7 andcomprises the hollow fork brace member 2a of rectangular cross sectionattached to steering post I as above described. Flat sided cross member8a extends through said hollow brace member and fork members II and I2are rigidly attached to studs 9a and Illa thereof. Said iiat crossmember is mounted between rubber blocks I9 and 20 which ll the spacebetween such member and fork brace 2a. As in the previously describedform of mounting, wing portions Ia and I'Ia are provided to act asstops, preventing backward movement of the fork members beyond a certainpoint. Forward movement of such members is, however, only regulated bythe degree of compression of rubber blocks I9 and 20 as cross member 8aturns. Thus when a rider mounts the bicycle his weight will cause thefront wheel to move slightly forward and member 8a to rotate slightly ina counterclockwise direction. as viewed in Fig. 6. When an irregularityin the road is encountered the front wheel may move back until the stopsat the upper ends of the fork arms encounter wing members Ia and IIa.Forward movement of the front wheel is only limited by the degree theamount of shock is capable of compressing the rubber blocks.

Projecting forwardly from fork brace 2 is a bracket member 2| adapted tocarry a spot light or the like." It will also be readily understood thatother commonly employed structural features, such as truss rods and thelike, may be used in conjunction with the fork of my invention.

It is readily apparent that the objects of this invention have beenfully achieved and a fork for bicycles and the like provided embodying aresilient mounting eiective to overcome the severe jolting and jarringto which such structure is continuously subjected.

Other modes of applying the principle of my invention may be employedinstead o the one explained, change being made as regards the mechanismherein disclosed, provided the means stated by the following claim orthe equivalent of such stated means be employed.

I therefore particularly point out and distinctly claim as my invention:

A shock-proof fork for bicycles and the like comprising a fork brace, asleeve mounted therein, a pair of fork members, a cross-member rigidlyconnecting the upper ends of said fork members and passing through saidsleeve, a body of rubber between said sleeve and said cross-member andbonded thereto, such rubber being under torsional stress tending tocause said fork members to move rearwardly, stop means on said sleeveand said fork brace operative to limit rotation of said sleeve, in onedirection, and stop means on said brace adapted to engage the rear upperends of said fork members, limiting rearward movement of said forkmembers relative to said fork brace, whereby said fork members may moveforwardly against the torsional stress of said body of rubber to providecushioning action oi said fork members.

HARRY W. KRAN Z.

